McCord, R.D. and Boaz, D. eds. Southwest Paleontological Symposium - Proceedings 2000 Mesa Southwest Museum Bulletm NO.7 Mesa Southwest Museum and Southwest Paleontological Society Mesa, Arizona Copyright 2000 PROBOSCIDEAN FOSSILS FROM THE SAN SIMON RIVER VALLEY, GRAHAM AND COCHISE COUNTIES, ARIZONA.

B. J. Tegowski Richard S. White Southwest Paleontological Society Curator Southern Chapter International Wildlife Museum P.O. Box 1231 4800 Gates Pass Road Sonoita, Arizona 85637 Tucson, Arizona 85745

ABSTRACT

Fossil elephants have been reported from deposits in the San Simon River Valley since 1936. We record here all known occurrences of proboscideans from that area, and record the latest find, a nearly complete skull that was recovered in 1999. The skull represents an adult Columbian Mammoth (Mammuthus columbi) which was at least 45 years old at the time of its death. We also comment on the difficulty of allocating individual teeth to either Rhynchotherium or Cuvieronius and question a number of earlier identifications.

GEOGRAPHICAL AND GEOLOGICAL 1984). Wood reported "mastodon bone and teeth SETTING fragments" throughout the section at 111 Ranch, and based his specific identification on an M3 The part of the San Simon River Valley with (UA-83) from the "middle limestone unit" (Wood, which we are concerned begins near Safford, 1962:59). Wood compared his specimen to Arizona, where the San Simon River empties into Stegomastodon mirificus described by Savage the Gila River, and extends some 55 miles (1955) from the Panhandle of Texas. Galusha et al southeast to just east of San Simon, Arizona. (1984) do not include Stegomastodon in their faunal Although the San Simon Valley extends further list; presumably their listing of Rhyncotherium and south, none of the finds reported here were found Cuvieronius includes this specimen. south of San Simon. The valley is filled with gravels, sands, silts and clays collectively tenned 2. Rhynchotherium sp. Reported by Knechtel in the "Gila Conglomerate", of Pliocene age, which 1936 and 1938, from Bear Springs (map reference: are in tum overlain by a mantle of Pleistocene and SE I;4 of Section 9, T7S, R23E). A portion ofa skull Holocene gravels and sands. Thrasher (this with teeth, identified by C. L. Gazin from the volume) provides a useful summary of the geology Smithsonian Institution, on the basis of photographs of the area, which we will not repeat here. and casts of the tooth crowns.

HISTORICAL REVIEW OF 3. Rhynchotherium sp. Galusha and others (1984) reported the occurrence of Rhynchotherium sp. at PREVIOUS FINDS 1I I Ranch, although they do not provide the basis for that identification. I. Stegomastodon mirificus. Reported from 1I I Ranch in a dissertation done under John Lance's 4. Rhynchotherium falconeri Although collected supervision at the University of Arizona by Paul from the Duncan Valley east of the San Simon Wood (1962). This record is presumably the basis Valley. this specimen should be mentioned, for later records ofRhynchotherium (Galusha et ai, especially given other less complete records of

101 Rhynchotherium from the San Simon Valley. [t actually located in the NE 1;4 of Section 31. Chipped consists of a complete skull and lower jaw, with stone artifacts were reported as occurring 60 tusks collected in 1986. Tbe specimen is displayed centimeters above the tusk and 10 meters to the at the Las Vegas Museum of Natural History; a west. The artifacts are in the Arizona State Museum cast will be part of the new exhibit at the Mesa collection. It is surprising that this site was not Southwest Museum. Miller (1990) described the further investigated, given the exc itement caused by specimen in detail. similar finds at Double Adobe, located to the west in the Sulphur Springs Valley, in 1927. 5. Cuvieronius sp. Galusha and others (1984) report Cuvieronius as present in the III Ranch 9. Mammuthus sp. Saunders 1970 thesis, "The Fauna. They do not provide the basis for this Distribution and Taxonomy of Mammuthus in identification. Arizona", lists only a single record for mammoth in Graham County. He records "a few enamel plates" 6. "mastodon (or gomphothere)" Thrasher (this as having been found in the Whitlock Valley. The volume) mentions a poorly preserved proboscidean locality is A35 in the University of Arizona lower leg which was found between Dry Mountain Laboratory of Paleontology system; a precise and the Power Line in April, 1991 (map reference: location is not known. SW Y4 of Section 14, TIOS, R28E). Only a few toe bones were collected. Present location of the 10. Mammuthus sp. A "nearly complete" mammoth specimen is unknown. A photograph in the Bureau tibia was found in surficial, presumably Pleistocene, of Land Management (BLM) files shows the very gravels south of Safford in 1991 (map reference: deteriorated and weathered tibia, the tuber calcis of SW V4 of the NE 1;4 of the NW V4 of Section 29, the calcaneum, and miscellaneous toe bones T7S, R26E). This specimen is currently on display including sesamoids. at the BLM headquarters in Safford.

7. Mastodont, unident. A few toe bones of an II. Mammuthus sp. On file at the BLM office in unidentified mastodont were located in May of Safford is a record of a single mammoth tooth 1999 in the NW 1/4 of Section 9, T9S, R28E. From found February 1, 1991 along the banks ofthe San photographs in the BLM files, the preservation of Simon Creek 1/3 mile east of the mouth of Ryan these bones is such that it is assumed that they Draw (map reference: SE V4 of Section I, TIl S, came from the classic III Ranch fauna, and R28E). Photographs show a single tooth in presumably represent either Rhynchotherium or fragments, which appears to be an upper M 3/. Cuvieronius. 12. Mammuthus sp. Thrasher (ms) mentions a skull 8. Mammuthus sp. (7). BLM records include a with tusks, which was found in the Bowie zeolite report of a mammoth tusk found October 1, 1939 pit southwest of the Whitlock Mountains in March by Emil W. Haury and Florence Connolly. The site of 1992. The find is record as located in the NW 1;4 is recorded as Ariz CC: 12:2 in the Archaeological of Section 27, TIl S, R29E in the BLM files. This Site Files of the Arizona State Museum, which specimen is reported to be housed in the University include a sketch map made at the time of the of Arizona collections. One partial tusk is on dis­ discovery. The locality is given as 1Y2 miles east of play at the BLM office in Safford. Thrasher reports San Simon, 100 meters north of State Highway 86 this as Pleistocene in age. Photographs in the files where it crosses the San Simon Creek, on the west ofthe BLM office in Safford clearly show part ofa bank, in Cochise County. BLM records indicate the skull and one tooth still in place. No specimens site location as the NW V4 of Section 32, TI3S, were located in the University of Arizona R31E. Review of the records at the Arizona State collections. Museum, and the maps, indicates that the site is

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~ ..•. o 13. Mammuthus sp. A badly fragmented tusk of a mammoth skull. The managers of the quarry mammoth was found in February of 1996 a short immediately stopped work in the vicinity of the distance west of the skull mentioned in # 12 above find. The company then contacted Larry Thrasher (map reference: NW I;4 of Section 27, Til S, R29E). of the BLM office in Safford.

14. Mammuthus sp. Some miscellaneous bones of The part of the skull that was exposed included a mammoth were found in 1974 about 2 miles south the palate, molars and zygomatic arches. The skull ofSolomon. The location is in the NW I;4 of Section was lying face down with the palate oriented ap­ 36, T7S, R27E, on the west side of the San Simon proximately vertically. The wall containing the River. Dr. E. H. Lindsay and Kevin Moodie of the skull was facing north, approximately 30 feet high, University of Arizona Laboratory of Paleontology with the exposed portion located about two feet collected the material. Bones present are the right below the top of the wall. and left calcanea, the right astragalus, right meta­ tarsals II, III, and IV, and a partial thoracic vertebra. Mr. Thrasher examined the find on March 18th. Preservation of these specimens is excellent, with He treated the exposed parts of the skull with pre­ the bone indurated and dark brown in color. The servative, and directed the efforts of the Morris bones are from a very large individual; they match Sand and Gravel Company to stabilize the site. nearly identically the measurements of the type of Thrasher decided to wait until Dr. Everett Lindsay, Mammuthusjloridanus in the American Museum of of the University of Arizona, was available to Natural History as recorded by Osborn (1942: 1113). complete excavating the skull. During the night of These bones are not catalogued into the University March 19th or morning of March 20th, someone of Arizona collections. removed one of the teeth.

15. Mammuthus columbi The find reported in this Now increasingly concerned about the security paper, an eroded skull with teeth but no tusks, was of the site, Mr. Thrasher called the Mesa Southwest found in the spring of 1999 in a sand and gravel pit Museum and spoke to Doug Wolfe, Assistant about one mile south of Safford (map reference: SE Curator for Geology of Mesa Southwest Museum, I;4 of the SW 114 of the NE I;4 of Section 29, T7S, asking him ifthe Museum could provide assistance R26E). Privately owned, the disposition of this with excavating the skuII. Mr. Thrasher al so skull has not yet been decided. It was found one obtained assistance from Morris Sand and Gravel half mile to the SE of the tibia mentioned in # I O. Company, which provided two employees to begin Although Thrasher cites a personal communication excavation of the skull. By March 26, 1999, the from Dr. C. V. Haynes ofthe University ofArizona, overburden directly above the skull was removed to the effect that the tibia may have come from the and the occipital condyles and the back of the skull same animal as the skull, we see no basis for such were exposed. a conclusion. On March 26th, Dr. Robert McCord, of the DISCOVERY AND EXCAVATION OF Mesa Southwest Museum, requested that the South­ THE SAFFORD SKULL west Paleontological Society (SPS) assemble an emergency response team to salvage the skull. The On March 17, 1999, a heavy equipment oper­ Southwest Paleontological Society was able to send ator exposed a portion of a mammoth skull in the volunteers to the site on Sunday, March 28, 1999. wall of the sand and gravel pit owned by Morris On that day, volunteers gathered in Safford, led by Sand and Gravel Company in Safford, Arizona Doug Wolfe. (Figure I). The operator, recognizing what he had uncovered, went to the company's office and After viewing the site, the team determined that reported he had found what appeared to be a a substantial amount of sediment would have to be

104 removed from the area south of the skull in order After lunch, the volunteers removed the for heavy equipment and volunteers to safely access remaining pedestal and rolled the skull with its it. The Morris Sand and Gravel Company provided jacket onto the runners. This feat was accomplished a backhoe and operator to remove the overburden. without damaging the skull. The team then plastered the remainder of the exposed skull. With With the area around the skull prepared, the the help of one of the company's heavy equipment volunteers began to remove dirt from around the operators, the skull was then carefully lifted and skull by hand. When the skull was more fully placed into the bed of a pickup truck and exposed, the volunteers jacketed the exposed skull transported to Tucson for preparation and possible in plaster. By the time this portion of the skull was restoration. jacketed, it was evening and the volunteers had run out of plaster and burlap. Having achieved as much DESCRIPTION OF THE SKULL as possible in the available time, the team decided to stabilize the skull and to return to the site the The skull is that of an adult mammoth, lacking following weekend to complete the excavation. the upper portion ofthe occipital plane and adjacent portions of the top of the skull above the nasal In order to stabilize the skull for the week, the depressions and lacking the major part ofthe alveoli team piled stones on the north side to the bottom of for the tusks. Based on photographs taken at the the plasterjacket. The quarry operators then added time of the discovery of the skull, both zygomatic dirt and rocks to stabilize the wall. The team then arches were present, though damaged. The placed 2"x4" wooden props under the jacket, and remainder of the skull appeared to have been in the heavy equipment operators covered the props relatively good condition when it was first with more dirt and rock. With the north side thus uncovered (Figures 2-4). Clearly visible in these fortified, the skull was positioned so that if the photographs are the zygomatic arches and both of pedestal were to crack, the skull would roll into a the two functional upper molars. slight depression on the south side instead of dropping over the wall on the north side to the Preparation of the skull, at this only partially quarry floor. finished, shows that there was considerable damage done to the skull, both by the vandalism and by the Unfortunately, the return to the site on amount of time between discovery and eventual Saturday, April 3, had to be rescheduled due to bad jacketing and recovery. The bone of the skull is weather. The area received considerable rain on generally well preserved, but is quite fragmented. April 2 and the wet conditions created serious safe­ There is a major "fault" passing through the skull ty concerns. Volunteers returned on Saturday, April perpendicular to the palate, likely the result of 10 to finish the process of cutting away the pede­ having been suspended vertically in the wall of the stal, jacketing the remainder of the skull and gravel pit after discovery. removing it. Joining the volunteers that day was Mr. Jack Gilbert, President and CEO ofthe Morris Sand Vandals had removed one of the two teeth in and Gravel Company. the skull. The remaining tooth, the right M 3/, was removed from the skull by employees ofthe Morris The volunteers first removed part of the pede­ Sand and Gravel Company who feared that vandals stal and then embedded two paralleI2"x4" boards in would return for that tooth before the skull was the plaster jacket at the back of the skull. These properly salvaged. The tooth was badly broken up, runners would bear the weight of the skull and its but was largely reconstructable. Enamel thickness jacket when the skull was removed and transported measures 3.2 millimeters. The tooth is 15.0+ from the site. After plastering the runners in place, centimeters in height and 10.4 centimeters in maxi­ the team broke for lunch while the plaster dried. mum width. The lamellar frequency (the number

105 FIGURE 2. Locality 15 as it appeared prior to excavating J1ammuthus skull

FIGURE 3. Mammoth skull in situ at locality 15. Note the fine grained sediments above and to the sides of the skull. Photo Courtesy of L. Thrasher, BLM. of enamel plates in 100 millimeters) is 6 at the pebbles and some iron oxide banding. The deposit occlusal surface of the tooth. There are at least 17 does not appear to have been a channel cut into the ridge plates present in the tooth, and perhaps 18. gravels, as had originally been thought. These measurements accord most closely with the upper third molars of Mammuthus columbi We are tentatively interpreting the sequence of measured by Saunders (1970:35), and fit entirely events as follows: There was a high-energy event, within the range reported for the sample of responsible for the deposition of the gravels as a Mammuthus columbi from South Carolina by whole, part of which involved moving the skull to Osborn (1942: 1076). From the stage of wear of the the northeast from where it originally lay. With the tooth, we conclude that" the animal was at least 45, tusks detached, the skull would have been the most and possibly 50 (elephant) years old at the time of buoyant portion of the skeleton. It was, therefore, death (based on data in Roth and Shoshani, 1988). probably carried the greatest distance by the water.

Most of the missing portions of the skull were During the transport and deposition ofthe skull, destroyed either before or at the time of its deposi­ it was rolled and abraded, with damage done to the tion. The top of the skull extended into the gravel top of the skull and to the alveoli for the incisors. and pebbles up to about 5 inches in maximum di­ Subsequently, a low energy event, possibly sheet mension were found wedged in the exposed cancel­ wash or over-bank flooding, was responsible for lous bone. The thin bone in the nasal depressions depositing the fine silty sands in a depression which was broken, with gravel extending into the skull. surrounded the skull. The depression was the result of the presence of the skull during the terminal DISCUSSION phase of the high-energy regime.

Because no other bones or fragments were AGE OF THE DEPOSITS AND found at the site, it appears that the mammoth died, INCLUDED PROBOSCIDEAN FOSSILS: and its skeleton became disarticulated, somewhere southwest of the dig site (presently and historically Thrasher (this volume) provides a concise, up slope from the site). The tusks became detached useful summary ofthe investigations that have been before the skull was deposited. made concerning the "Gila Conglomerate". As Thrasher notes, the term has never been formally The skull rested on, and extended a short defined. It is worth noting here that this term is not distance into, the poorly sorted gravels which strictly a lithostratigraphic term, since materials of blanket the area. These gravels represent high­ widely varying and laterally gradational lithologies energy deposits, possibly braided stream deposits, are included. It is also not a chronostratigraphic and show evidence of locally variable current term, since the age is largely based on the inferred directions. The skull lay in a lens shaped depression ages of the included faunas; nor is it a biostrati­ that was traceable on three sides of the skull (south, graphic term, since it has been applied in many east and west). The dimension of the lens in the sections where no included fossils have been East-West section through the skull was approxi­ identified. It seems rather to be a term based largely mately 10-12 feet. The extent of the lens to the on the structural geology of the sediments. The south of the skull was not recorded, and this part of lacustrine sediments in which the classic 111 Ranch the deposit was removed in order to gain access to Fauna is found have been determined to be Late the skull. The deposits immediately to the north of Pliocene (Blancan Land Mammal Age, Galusha et the skull had been removed by the quarrying aI, 1984). operation that originally uncovered it. This deposit thinned laterally in all three directions, and con­ The surficial gravels and alluvium in the San sisted ofa fine, silty sand with a few included small Simon Valley have not been precisely dated, other

107 FIGURE 4. Bones of Mammuthus sp From locality 14: A. right calcaneum; B. left calcaneum; C. right astragalus D. right metatarsal II; E. right metatarsal III; F. right metatarsal IV than to say that they are Quaternary in age, that is, already been shown to be variable (Miller, 1990: Pleistocene or Holocene. Some of the gravels are 66, Table 2). This makes identifications of either relatively recent, as they contain stone tools from genus questionable on the basis of individual teeth the Cochise Culture (see locality 8); these same or where intermediate stages are present. gravels, though at a slightly lower level, include mammoth materials which may be reworked from Even complete skulls may be difficult to older deposits, much as was the case in the Sulphur identify at this point, since, as Miller (1990) points Springs Valley to the west, at the Double Adobe out, many of the characters previously used to Site (Haury, 1959). define species, particularly of Rhynchotherium, are quite variable. Relatively primitive Rhynchotherium Miller (1990) has suggested Rhynchotherium may be differentiated from advanced Cuvieronius was the ancestor of Cuvieronius, and his Arizona with more confidence. Galusha et al (1984) state specimen represents a late Rhynchotherium with that both genera appear to be present in the III advanced characteristics. Differentiating isolated Ranch collections, but do not provide information molar teeth from animals dating to the transition as to the basis of their identification. Shaw (1981), would be difficult; other characters listed by Miller, in identifying the EI Golfo gomphothere, discusses such as the absence of lower incisors in Cuvier­ only Stegomastodon and Cuvieronius, concluding onius, enamel banding on the tusks and develop­ that a partial lower M3 is referable to Cuvieronius. ment of post-trite trefoils on the molars, have

108 FIGURE 5. Top, lateral view of right upper M3, Mammuthus columbl from locality 15. Bottom, occlusal view of right upper M3. A fragmentary mandible lacking the symphysis mined that if the skull is well enough preserved, it and any tooth crowns, was referred to Cuvieronius will be placed on display in a local museum. We on the basis ofthe M3 from the same formation. We thank Peter Vlassis, PE, for using his Sunday see nothing, based on Shaw's description and illus­ morning and afternoon to provide backhoe operator tration, which would preclude his M3 from assign­ services and providing the authors with digital ment to either Rhynchotherium or Cuvieronius. images of the fossil and the excavation. Larry Cuvieronius appeared in North America in the Thrasher of the Safford BLM office arranged to Blancan, and occurs through the Rancholabrean have the Mesa Southwest Museum excavate the (Lambert 1996: 145). Miller (1990), based partially fossil and shared photographs and information with on the date of the III Ranch Fauna, and partially the authors. Kevin Moodie, University of Arizona on the stage of evolution of the Rhynchotherium Laboratory of Paleontology provided access to skull he reported, surmised that it is "late, if not specimens and records, and provided a modem latest, Blancan in age". Rhynchotherium is known elephant foot for comparison. Sharon Urban pro­ elsewhere in North America from the Late Hem­ vided information from the Arizona State Museum phillian through Late Blancan (Lambert 1996: 144); Archaeological Site Files. The Las Vegas Natural it is known from the Late Clarendonian or Early History Museum provided photographs of the Hemphillian of Central America (Webb and Duncan Rhynchotherium. Mary Odano, Valley Ana­ Perrigo, 1984). tomical Preparations, supplied us with a copy of Osborn's Proboscidea monograph, which was Mammuthus does not occur in North America unavailable in Tucson. In addition to the authors, prior to the Early Irvingtonian Land Mammal Age. the following SPS members participated in the It is known throughout the Irvingtonian and Ran­ excavation: Kathy Benson, Kile Benson, Phil cholabrean, and so cannot, at the generic level, re­ Eklund, Richard Fedele, Milt Smith, Mike (Doug's fine the age of the deposits beyond Pleistocene. No friend), Lorraine Thomas and Carolyn White. Irvingtonian finds of Mammuthus have been de­ Carolyn also provided helpful editorial advice. scribed from Arizona, although mammoths are known from the Irvingtonian El Golfo Fauna at the REFERENCES head of the Gulf of California in Sonora, Mexico. GALUSHA, T, Johnson, N.M., Lindsay, E.H., Updyke, N.O. and Shaw (1981) identifies the mammoth material from Tedford, R.H., 1984. "Biostratigraphy and magnetostratigraphy, El Golfo as Mammuthus imperator based on "the Late Pliocene rocks, III Ranch, Arizona" Geo. Soc. of Am. Bull., Vol. 95714-722. measurements and plate frequency, and given the thick enamel and fairly high crowned condition" of KNECHTEL, M.M., 1938. "Geology and Groundwater Resources of two fragmentary enamel plates of an upper M3. the Valley ofGila River and San Simon Creek, Graham County, Arizona". US Geo. Survey, Water Supply Paper 796-F. While preservation is a notoriously unreliable way to date individual fossils, we note that the Rancho­ KNECHTEL, M.M., 1936 "Geological Relations of the Gila Conglomerate in Southeastern Arizona" Am. Jour. of Sci., Vol. labrean mammoth material from southern Arizona 31 (182):81-92. is usually light in color, and quite friable and por­ ous. The mammoth bones noted at locality # 14 are LAMBERT, W.o., 1996 "The biogeography of the gomphotheriid proboscideans of North America" The Proboscidea: Evolution heavily mineralized, and dark in color, which might and Palaeontology of Elephants and Their Relatives. suggest that they are older than the other finds of Mammuthus we report. MILLER, W.E., 1990 "A Rhyncholherium Skull and Mandible from Southeastern Arizona". Brigham Young University Geology Studies, Volume 36: 57-67. ACKNOWLEDGMENTS OSBORN, H.F., 1942 Proboscidea, a Monograph on the Diversity, The authors would like to thank Jack Gilbert III, Evolution, Migration and Extinction of the Mastodons and PE, President and CEO of Morris Sand and Gravel Elephants of the World, Volume 2 Company Inc. for his hospitality, efforts and assist­ ROTH, V.L. and Shoshani, J, 1988 "Dental identification and age ance in preserving this fossil. Mr. Gilbert has deter­ determination in Elephas maximus". Journal of the Zoological Society of London (1988), 214: 567-588.

110 SAUNDERS, U., (1970). The Distribution and Taxonomy of WEBB, S.D. and Perrigo. S.C, 1984 "Late Cenozoic Vertebrates from Mammuthus in Arizona, Unpub. Master's Thesis, Univ. of Ariz.. Honduras and EI Salvador" Jour. of Vert. Paleo., Vol. 4 237-254

SHAW, CA, 1981 The Middle Pleistocene EI Golfo Local Fauna from WOOD, P.A .. 1962 Pleistocene fauna from III Ranch area. Graham Northwestern Sonora, Mexico, Unpub Master's Thesis. Calif County. Arizona. Unpublished Ph.D. Dissertation. Univ. of Ariz State Univ. at Long Beach.

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